In the Garden:Coastal and Tropical South
February, 2005
Regional Report

What Not to Plant

There are many unruly exotics, quite a few thugs, and more than a few truly invasive species that gardeners should be aware of and avoid. Water hyacinths, Chinese tallow trees (a.k.a. popcorn), and littleleaf privet are some common examples. Each was imported for its beauty and economy without an understanding of its impact on native ecosystems. Nothing much eats them, and our growing conditions are beyond ideal for their propagation.

Worst of the Worst
Water hyacinths are prized in cold climates, but they clog our bayous. In your backyard water garden, they will soon overtake lilies and even water lettuce, simply because they grow faster.

Chinese tallow trees were touted as the perfect fall color tree. Their reliable red and purple hues are dramatic, and after they drop, the silhouette is no less so, covered as it is with white seedpods (thus "popcorn"). But therein lies the problem with this type of invader: nearly every seed sprouts and grows into a woody stem, if not an entire tree. Whole wetlands are choked with tallow trees, and planting them is prohibited in some areas.

Privet is an example of a "black sheep" of a good plant family, as is Japanese honeysuckle. A privet relative, glossy-leaved ligustrum is not invasive, nor is coral honeysuckle, but their rogue kin cause serious damage in our region. They spread underground and by seeds, and their presence spells doom for native species, which are shaded or crowded out by the aggressive exotics.

Dealing With Invasives
We all can help by avoiding planting recognized invasives in our gardens, and keeping an eye on new introductions we're not familiar with. If you acquire a property, do a plant census during the first year. If invasives are present, make a plan to remove them. Getting rid of bullys, especially woody species like privet and honeysuckle, is not easy. Recommendations for spraying range from herbicides that kill only the top of the plant and do nothing to control regrowth from the roots, to brush killers that can suppress everything in the soil, including native seedlings.

Physical removal, daunting though it may seem, is often the best answer, whether done in conjunction with spraying the tops or not. Wet soil, sharp shovels, and innovative prying tools make this essential garden chore less daunting, but it is full body exercise of the highest order and worth all the sweat.